BuddyPress.org

Try this in your style.css:

/* Inherit the default theme styles */

@import url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/default.css );



/* Inherit the default theme adminbar styles */

@import url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/adminbar.css );



#header {background:#121212 !important;}

Make sure you refresh your page so you can view the new changes.